JP5599036B2 - Liquid discharge head - Google Patents

Description

  The present invention relates to a liquid discharge head used in a continuous liquid discharge apparatus.

  A continuous ink jet apparatus (liquid ejection apparatus) applies pressure to ink at all times by a pump to push out ink. Further, the ink ejected by the vibrating means is vibrated to create a droplet forming state called a Rayleigh jet, thereby ejecting the droplets regularly from the nozzles. In the continuous method, since ink is continuously ejected from the nozzles, it is necessary to select the droplets used for printing and the droplets not used according to the print data. For this purpose, the droplets are selectively charged and deflected by an electric field so that they traverse a different trajectory from the uncharged droplets. In a continuous ink jet apparatus called a binary system, uncharged droplets are used for printing, and charged droplets are captured and collected by a gutter.

  In a continuous inkjet apparatus, a plurality of nozzles arranged in a straight line is known in order to obtain a high-definition image. Patent Document 1 discloses a modular multi-jet deflection head including a plurality of nozzles arranged in a row. The deflection electrode in Patent Document 1 is prepared by preparing members formed by patterning wiring on the upper surface and lower surface of the electrode plate, and individually drawing one pole to the upper surface of the electrode and the other electrode to the lower surface. The deflection electrode has a structure in which two kinds of poles are alternately arranged in the electrode plate.

Japanese Patent No. 3260416

  By the way, in order to realize high speed printing and high definition, it is effective to increase the number of nozzles and arrange the nozzles in a two-dimensional array at high density. In Patent Document 1, in order to obtain a high resolution, a two-dimensional array is prepared by preparing a plurality of modules and combining them on the side.

  However, high accuracy is required for assembling modules, and as the number of nozzle arrays increases, the number of assembling steps increases and the manufacturing cost increases.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a continuous liquid discharge head that can obtain high resolution and is low in manufacturing cost.

A liquid discharge head according to the present invention has a plurality of nozzles for discharging droplets arranged two-dimensionally along a first direction and a second direction different from the first direction. Nozzle member, charging member having a charging electrode for applying a charge to droplets ejected from each of the plurality of nozzles, and deflecting each of the droplets charged by the charging electrode of the first deflection member and the second deflection member having a deflection electrode, respectively, wherein the charging member, the first deflection member, and the second deflection member, said plurality of Each of the plurality of nozzles has a through hole for allowing a droplet discharged from the nozzle to pass therethrough, and the charging member, the first deflecting member , and the second deflecting member are in this order. It is laminated in the direction in which droplets are discharged from Ri, the second deflection member has a conductive surface which corresponds to each of the plurality of nozzles in each of the inner wall of the through hole, the second deflection member facing each other in the first direction The conductive surface of the liquid crystal defines a droplet flight path so as to sandwich an entrance trajectory axis of both droplets from two adjacent nozzles therebetween, and the first deflecting member is the second deflecting member. And a protrusion having a conductive surface protruding toward the through-hole of the deflection member and constituting the deflection electrode .

  According to the present invention, a high-speed and high-definition liquid discharge head can be obtained, and a liquid discharge head with a low assembly cost can be obtained in which the number of parts does not increase even when the number of nozzle arrays is increased.

It is a system outline figure of an example of an ink jet device to which the present invention is applied. 1 is a perspective view and an exploded perspective view of an inkjet head according to an embodiment of the present invention. It is sectional drawing of the inkjet head of FIG. FIG. 4 is a top view of the inkjet head of FIG. 3. It is process drawing of the orifice plate which concerns on a 1st Example. It is process drawing of the charging electrode plate which concerns on a 1st Example. It is process drawing of the 1st deflection | deviation electrode plate which concerns on a 1st Example. It is process drawing of the 2nd deflection | deviation electrode plate which concerns on a 1st Example. It is a top view of the 2nd deflection | deviation electrode plate which concerns on a 1st Example. (A) is a figure which shows the result of the electric field simulation in the deflection electrode plate of 1st Example, (B) is a perspective view which shows the model of the electric field simulation in the deflection electrode plate of 1st Example. . It is process drawing of the 1st deflection | deviation electrode plate which concerns on a 2nd Example. It is process drawing of the 2nd deflection | deviation electrode plate which concerns on a 2nd Example. It is a top view of the 2nd deflection | deviation electrode plate which concerns on a 2nd Example. It is process drawing of the 2nd deflection | deviation electrode plate which concerns on a 3rd Example. It is sectional drawing of the inkjet head which concerns on a 4th Example. It is a top view of the 2nd deflection electrode board manufactured with the 1st manufacturing method concerning the 4th example. It is process drawing by the 2nd manufacturing method of the 2nd deflection | deviation electrode plate which concerns on a 4th Example. It is process drawing by the 3rd manufacturing method of the 2nd deflection | deviation electrode plate which concerns on a 4th Example. (A) and (b) are the top views of the 2nd deflection | deviation electrode plate manufactured with the 2nd manufacturing method which concerns on a 4th Example, (c) (d) is the 4th which concerns on a 4th Example. 6 is a top view of a second deflection electrode plate manufactured by the manufacturing method 3 in FIG. (A) is a figure which shows the result of the electric field simulation in the deflection electrode plate which concerns on a 4th Example, (B) is a figure which shows the model of the electric field simulation in the deflection electrode plate which concerns on a 4th Example. is there. It is sectional drawing of the inkjet head which concerns on a 5th Example. It is a perspective view of the 1st deflection | deviation electrode which concerns on a 5th Example. (A) (b) is process drawing by the 1st manufacturing method of the 1st deflection | deviation electrode which concerns on a 5th Example, (c) (d) (e) is the 5th which concerns on a 5th Example. It is process drawing by the 2nd manufacturing method of 1 deflection | deviation electrode. (A) is a figure which shows the result of the electric field simulation in the deflection electrode plate which concerns on a 5th Example, (B) is a figure which shows the model of the electric field simulation in the deflection electrode plate which concerns on a 5th Example. is there.

[First Embodiment]
A first embodiment of the present invention will be described. In this embodiment, an ink jet apparatus is described. However, the present invention is not limited to the case of discharging printing ink using a color material, and can be applied to discharge of other liquids in general.

  FIG. 1 is a system schematic diagram of an ink jet apparatus equipped with the ink jet head of the present invention. The ink jet apparatus of the present invention includes an ink tank 001, a pressure pump 002, a vibration mechanism 003, a head 004, a recovery pump 006, and an ink adjustment unit 007. FIG. 2 is a perspective view and an exploded perspective view of the head (however, the gutter is not shown). FIG. 3 is a cross-sectional view of the head. FIG. 4 is a top view of the head.

  The head will be described in more detail with reference to FIGS. The head 004 includes an orifice plate 101 as a nozzle member, a charging electrode plate 102 as a charging member, a first deflection electrode plate 103 as a first deflection member, and a second as a second deflection member. A deflection electrode plate 104 is included. Further, the head 004 includes a gutter 005 and insulating spacers 201, 202, 203.

  The constituent members of the head 004 have a plate shape and are stacked in the ink flying direction. That is, insulating spacers as insulating members are interposed between the orifice plate 101, the charging electrode plate 102, the first deflection electrode plate 103, and the second deflection electrode plate 104, respectively.

  In the orifice plate 101, a plurality of nozzles that eject ink are arranged in a two-dimensional manner along a first main direction (first direction) and a second main direction (second direction). Yes. The charging electrode plate 102 is provided with a through hole through which the discharged ink passes, and an electrode is formed on the inner wall of the through hole. The electrodes are connected to the wiring, and a charging voltage can be applied to individually apply charges to the ink droplets.

  The first deflection electrode plate 103 is provided with a through hole through which the discharged ink passes. An electrode is formed on the first deflection electrode plate 103, and the position of the electrode is either the inner wall surface of the through hole, the surface facing the second deflection electrode plate 104, or both. Unlike the electrodes of the charging electrode plate 102, the electrodes of the first deflection electrode plate 103 do not need to be individually applied with a voltage. Therefore, the electrodes corresponding to the through holes are wired to each other so as to have the same potential. You may be connected by. Alternatively, the first deflecting electrode plate 103 may be made of a conductive member so that the entire member has the same potential, and patterning of electrodes and wiring in the electrode plate may be omitted.

  The second deflection electrode plate 104 is provided with a through hole through which the ejected ink passes, and an electrode is formed on each inner wall thereof. Unlike the electrodes of the charging electrode plate, the electrode portions do not need to be individually applied with voltages, and therefore, the electrodes are connected by wiring so that they all have the same potential. By forming the second deflection electrode plate 104 with a conductive member, patterning of electrodes and wirings may be omitted. Further, the second deflection electrode plate may be made of a porous member so that it can also be used as a gutter.

  Next, the operation of the ink jet apparatus of the present invention will be described. The ink stored in the ink tank 001 is pressurized by the pressure pump 002 and supplied to the head 004. The ink supplied to the head 004 is vibrated by the vibration mechanism 003 and ejected from the nozzle 111. When the ink ejected from the nozzle 111 flies about 1 mm, it splits from the liquid column into droplets. The charging electrode plate 102 is installed so as to pass through the through hole at a position where the charging electrode plate 102 is divided into droplets. If a voltage is applied to the electrode during the breakup, the droplet is charged. If no voltage is applied, the droplet is not charged. Therefore, in accordance with the print data, the voltage applied to the charging electrode is controlled so that the droplets used for printing are not charged and the droplets not used for printing are charged. Thereafter, the uncharged droplets fly linearly and land on the print medium. A voltage is applied between the first deflection electrode plate (first deflection member) 103 and the second deflection electrode plate (second deflection member) 104, and the charged droplets are two deflection electrodes. As it passes through, it is deflected by the electric field. The deflected droplet is collected by the gutter 005. The collected ink is sucked by the collecting pump 006, and after removing dust and adjusting the viscosity by the ink adjusting unit 007, the ink is pressurized again by the pressure pump 002 and circulated to the head 004 for printing. .

  Ink is electrically conductive for charging. Therefore, the gutter 005 and the orifice plate 101 are electrically connected by the circulating ink. Since the second deflection electrode plate 104 often conducts with the recovered liquid droplets, the voltage applied to the supply ink, the charging electrode, and the deflection electrode is determined by the voltage between the supply ink and the second deflection electrode plate 104. Is preferably set to 0 V (GND), and a voltage is preferably applied to the charging electrode and the first deflection electrode.

  Next, a first embodiment of the present invention will be described.

  First, the manufacturing method of the inkjet head of this invention is demonstrated. First, a method for manufacturing the orifice plate 101 will be described with reference to FIG. As the substrate 301, an SOI (Silicon On Insulator) wafer is used. The handle layer has a thickness of 300 μm and a crystal plane orientation of (100). The BOX layer 302 has a thickness of 0.2 μm, and the device layer has a thickness of 3 μm.

  In the first step shown in FIG. 5A, a silicon nitride film 303 to be a mask is formed on both surfaces of the substrate. FIG. 5A shows a state in which the device layer of the SOI wafer is on the bottom. For the formation of the silicon nitride film 303, a process such as CVD can be used. Further, a silicon oxide film may be formed by thermal oxidation instead of the silicon nitride film.

  The second step shown in FIG. 5B is a step of producing individual flow paths 304 corresponding to the respective nozzles. The silicon nitride layer on the handle layer side of the substrate 301 is patterned by photolithography, and the handle layer is etched using the silicon nitride layer as a mask. For etching the handle layer, anisotropic wet etching is used. As the etchant, KOH (potassium hydroxide) can be used. In this etching, the etching rate varies greatly depending on the crystal plane of silicon, and therefore tapered etching is possible as shown in FIG. The tapered portion of the silicon after the etching has a structure in which the surface with the crystal plane orientation (111) is exposed. In addition, for KOH wet etching, the etching rate of silicon oxide is much slower than that of silicon, so that the etching stops at the BOX layer of the SOI substrate. If the mask has a square shape, the etched shape is a trapezoidal trapezoid. In this embodiment, the nozzle interval is 500 μm, and the width of the channel bottom after etching is 20 μm. In this embodiment, anisotropic wet etching is used, but individual channels can also be formed by deep dry etching using ICP-RIE. In this case, the etching is not tapered and silicon can be etched vertically. When this method is used, there is an advantage that it is not necessary to define the plane direction of the substrate, and a circular pipe-shaped individual flow path can be formed by making the mask shape circular. On the other hand, the use of the above-described anisotropic wet etching has an advantage that a plurality of substrates can be etched at the same time, and a tapered flow path has a low flow resistance and a high strength individual flow path.

  In the third step shown in FIG. 5C, the nozzle orifice 305 is formed. The silicon nitride layer on the device layer side (the lower surface in FIG. 5C) of the substrate 301 is patterned, and the device layer is etched using the silicon nitride layer as a mask. An alignment mark is provided on the mask used in the process of FIG. 5B and the process of FIG. 5C, and the center of the orifice coincides with the center of the individual flow path based on the alignment mark. Match the mask as follows. For etching, dry etching by RIE is used. Etching stops at the BOX layer of the SOI substrate because the etching rate of silicon oxide is very slow compared to silicon. In this embodiment, the orifice diameter is 7.4 μm.

  The fourth step shown in FIG. 5D is a step of removing the silicon nitride layer on the substrate surface and the BOX layer at the bottom of the individual flow path by etching and penetrating between the individual flow path and the nozzle orifice. For the etching, wet etching using BHF (buffered hydrofluoric acid) is used. Note that a silicon nitride layer or a silicon oxide layer may be formed on the surface of the flow path in order to improve the corrosion resistance after the step.

  As described above, the orifice plate of the present invention can be manufactured. In addition to the manufacturing method of the orifice, there are a method of forming a metal plate by etching, pressing or laser processing, or a method of forming by using electroforming.

  Next, a manufacturing method of the charging electrode plate 102 will be described with reference to FIG. First, a silicon wafer having a thickness of 500 μm is used as the substrate.

  In the first step shown in FIG. 6A, an etching mask 402 is formed on the substrate 401. Cr or the like can be used as the substrate material. Cr is deposited on the substrate surface, and then patterned by photolithography.

  The second step shown in FIG. 6B is a step of forming a through hole 405 through which ink passes, using the mask 402 created in the first step. By using ICP-RIE for the etching of the through hole, high aspect ratio deep etching can be performed. In this embodiment, the through hole has a circular cross section and the hole diameter is 300 μm. After the etching, Cr used for the mask is removed by etching.

  In the third step shown in FIG. 6C, a conductive layer is formed on the substrate surface and the inner wall of the through hole by plating. Electroless plating of Au is used.

  In the fourth step shown in FIG. 6D, a film-like resist 407 is formed on the substrate surface. A laminator is used to form the resist so that the surface of the through hole 405 is also covered. Further, by patterning the film resist, an electrode pattern is formed on the substrate surface (the same applies to the back surface of the substrate 401).

  In the fifth step shown in FIG. 6E, the conductive layer on the substrate surface is etched based on the resist pattern produced in the fourth step. Further, the wiring layer 403 is formed by removing the resist.

  In the sixth step shown in FIG. 6 (f), the surface of the wiring 403 is covered with a covering protective film 404. As the coating material, a material excellent in insulation and corrosion resistance such as parylene or polyimide is used. Parylene can be formed by CVD, and polyimide can be formed by spin coating. These materials are characterized by high coverage even when there are steps.

  As described above, the charged electrode plate of the present invention can be manufactured. Although the case where a silicon wafer is used as the substrate has been described, photosensitive glass may be used as the substrate. In this case, wet etching is used to form the through hole. Compared to silicon, the insulation of the substrate is superior. On the other hand, the processing accuracy of the through hole is higher when silicon is used as the substrate. Further, although the electrode 406 is formed by plating, a conductive material may be formed on the inner wall of the through hole 405 by oblique vapor deposition or the like.

  Other methods of manufacturing the charged electrode plate include firing a ceramic material, patterning the wiring on the surface, and forming electrodes by plating, or forming through holes in the printed board material with a laser, There is a method of forming an electrode.

  Next, a manufacturing method of the first deflection electrode plate 103 will be described with reference to FIG. As shown in FIG. 7A, a conductive member having corrosion resistance such as stainless steel is used for the substrate 501. In this embodiment, the substrate thickness is 200 μm. As shown in FIG. 7B, a through hole 502 through which ink passes is formed. In this embodiment, the through hole 502 has a circular cross section and a hole diameter of 50 μm. Etching, pressing, laser processing, or the like can be used to form the through hole 502. Furthermore, in order to improve conductivity and corrosion resistance, the electrode plate surface may be plated with gold.

  Next, a method for manufacturing the second deflection electrode plate 104 will be described with reference to FIG. In particular, here, a manufacturing method having a configuration in which a gutter and an ink recovery path are integrated for further miniaturization will be described. However, the manufacturing method may be separately prepared and installed. A conductive member having corrosion resistance such as stainless steel is used for the substrate shown in FIG. In this embodiment, the substrate thickness is 800 μm.

  In the first step shown in FIG. 8B, an ink flying path 602 through which ink passes and an ink collection path 603 for collecting ink are formed. As shown in FIG. 8B, the ink collection path 603 is formed in a slit shape extending in the depth direction. On the other hand, the flight path 602 is formed in a slit shape (FIG. 9A) extending in the depth direction, as shown in FIG. 8B. Alternatively, the flight path 602 is configured by individual through holes (FIG. 9B) extending from the front surface to the back surface of the substrate corresponding to each droplet row passing therethrough. For forming the ink flight path 602 and the ink recovery path 603, etching, pressing, laser processing, or the like can be used.

  In the second step shown in FIG. 8C, an ink flight path 605 through which ink passes is formed on the second substrate 604. The thickness of the second substrate is 100 μm. Etching, pressing, laser processing, or the like can be used for forming the ink flight path 605.

  The third step shown in FIG. 8D is a step of bonding the first substrate 601 and the second substrate 604. The two substrates are positioned so that the ink flight paths 602 and 605 coincide with each other, and are bonded to cover the upper part of the recovery path. An epoxy adhesive or the like can be used as the adhesive.

  Next, a process for forming a gutter will be described. Stainless steel or the like is used for the substrate of FIG. Here, the thickness is 100 μm. As shown in FIG. 8F, an ink flying path 607 and an ink recovery path 608 are formed. As a processing method, etching (step etching using masks having different shapes on both surfaces), press processing, or the like can be used.

  Finally, as shown in FIG. 8 (g), the two substrates are formed so that the ink flight paths 605 and 607 match the member manufactured in the step of FIG. 8 (d) and the member manufactured in FIG. 8 (f). Position and glue.

  As described above, the second deflection electrode plate (second deflection member) having the ink flight path (through hole) 609, the gutter 611, and the ink recovery path 610 can be formed. Furthermore, in order to improve conductivity and corrosion resistance, the electrode plate surface may be plated with gold. Further, when the substrate 601 is thick and it is difficult to process with high accuracy, a plurality of thinner substrates may be prepared, processed, and bonded together.

  The orifice plate 101, the charging electrode plate 102, the first deflection electrode plate 103, and the second deflection electrode plate 104 (including the gutter and the ink collection path) manufactured by the method described above are stacked as shown in FIG. Thus, the ink jet head is completed. Further, when laminating, by sandwiching an electrically insulating spacer between the members, the distance between the members can be kept constant and the members can be electrically insulated.

  In this way, each member has a through-hole through which ink passes, and since these members are stacked in the ink flying direction, there is an advantage that the number of parts does not increase even when the number of nozzles increases. In particular, since the first deflection electrode plate 103 and the second deflection electrode plate 104 are conductive plate-like members, it is not necessary to perform wiring patterning on each electrode plate, and the structure is very easy to process. ing.

Next, the operating conditions of the ink jet apparatus of this embodiment will be described. The nozzle diameter is 7.4 μm, and the pressure of the pressure pump 002 is 0.8 MPa. The vibration frequency of the vibration mechanism 003 is about 50 kHz. In this case, the droplet size is 4 pL and the discharge speed is about 10 m / s. The flying droplet is decelerated by the air resistance and is about 8 m / s when passing through the first deflection electrode plate 103. The charge amount at the charging electrode is −6 × 10 ⁻¹³ [C], the potential of the first deflection electrode plate 103 is −100 [V], the potential of the second deflection electrode plate 104 is 0 [V], and deflection is performed. When the equipotential lines of the electric field at the electrode and the trajectory of the charged droplet are simulated, the result is as shown in FIG. Three-dimensional nonlinear electrostatic field analysis software ELFIN (Elf Company) was used for the simulation. A perspective view of the structural model used in the simulation is shown in FIG. An equipotential line is formed between the lower surface of the first deflection electrode plate 103, the upper surface of the second deflection electrode plate 104, and the inner wall of the through hole, and the shape thereof is the through hole of the second deflection electrode plate 104. Is substantially mirror-image-symmetric with respect to the central axis. (To be precise, the axis of symmetry is the center line between the electrode surfaces of the inner wall portion of the second deflection electrode plate 104. Further, the axis of symmetry is strictly affected by the through hole of the first deflection electrode plate 103. Is not mirror-image-symmetric.) Since the electric field lines are perpendicular to the illustrated equipotential lines, when a negatively charged droplet enters from the right side with respect to this central axis, it is deflected to the right and enters from the left side. It is deflected positively (when the polarity of the charging electrode or the polarity of the deflection electrode is reversed, it is deflected in the reverse direction). In this example, the orbit axis of the droplet entering the through hole is shifted 50 μm to the left in the first main direction from the central axis of the through hole of the second deflection electrode plate 104. Accordingly, the charged droplet receives an electrostatic force so as to be deflected to the left, and draws a trajectory shown in FIG. The charged droplet is deflected by 42 μm at the lower end of the second deflection electrode. This is collected by gutter (gutter 005 in FIG. 3 is not shown in this simulation). On the other hand, uncharged droplets are not deflected, fly linearly, and land on the print medium below.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the present embodiment, another method for manufacturing the first deflection electrode plate 103 and the second deflection electrode plate 104 in the first embodiment will be described. In the first embodiment, a method for manufacturing these members using a conductive substrate is described. However, in this embodiment, the members are manufactured by forming a conductive film on the surface of an insulating substrate.

  First, a method for manufacturing the first deflection electrode plate 103 will be described with reference to FIG. The substrate shown in FIG. 11A is a silicon wafer. In this embodiment, the one having a thickness of 200 μm is used. First, a through-hole (ink flight path) 702 is formed on the substrate 701 by ICP-RIE (FIG. 11B). As the etching mask, a thermal oxide film or aluminum film previously formed and patterned by photolithography is used. Next, a metal to be an electrode is formed (FIG. 11C). A metal thin film having corrosion resistance such as Au is suitable for the electrode 703. In order to improve adhesion to the substrate, it is preferable to form a thin film of Ti or the like as a base layer. In the figure, a metal layer is also formed on the side surface of the electrode, but if there is a metal layer on the upper surface, it plays a role as an electrode. However, in order to prevent charging when ink mist adheres, it is preferable that the side wall of the through hole 702 also has a metal layer. For example, if vacuum deposition is used to form the metal layer, it is difficult to form a film on the inner wall, and if sputtering is used, it is easy to form a film on the inner wall.

  When assembling the first deflection electrode plate 103 produced in this manner, if the surface on which the electrode is formed is disposed so as to face the second deflection electrode plate 104, compared to the first embodiment, The electrode surface can be kept away from the charging electrode plate. Thereby, there is an advantage that the electric field of the first deflection electrode plate 103 can have a smaller influence on the charging process of the droplet. Furthermore, it can also be used as an insulating spacer by forming an insulating film layer on the electrode plate surface. Alternatively, the first deflection electrode plate 103 may be installed so that the surface on which the electrode is formed faces the charging electrode plate 102, and the substrate 701 may function as a negative insulating spacer. Accordingly, the third insulating spacer 203 can be omitted, and there are advantages that the number of parts is reduced and the distance from the nozzle to the printing medium is shortened.

  Next, a method for manufacturing the second deflection electrode plate 104 will be described with reference to FIG. In the first step shown in FIG. 12A, a mask for producing the upper portion of the second deflection electrode plate 104 is patterned. In this embodiment, a double-side polished silicon substrate having a thickness of 400 μm is used as the first substrate 801. First, a mask for etching the ink recovery path 804 and the ink flight path 805 is patterned. Here, the ink flying path 805 penetrates the substrate, whereas the ink recovery path does not penetrate the substrate, so two types of masks are required. Therefore, two-stage masks 802 and 803 are formed as shown in the figure. As the mask material, aluminum can be formed, or a silicon oxide film can be formed by thermal oxidation. These are patterned by photolithography. The two-stage mask is made of the same kind of material, and the two-stage masks are made by partially different thicknesses by two etchings or by laminating patterns of different materials.

  In the second step shown in FIG. 12B, the ink flying path 804 and the ink recovery path 805 are formed. Etching is performed by ICP-RIE using the two-stage mask manufactured in the first step. After etching the portion that becomes the ink flight path by the thickness (100 μm) of the upper wall of the ink recovery path, the second mask 803 is removed, and etching is performed using only the first mask 802. After the etching, the first mask 802 is removed.

  In the third step shown in FIG. 12C, the lower portion of the second deflection electrode plate 104 is formed. As the substrate, a double-side polished silicon substrate having a thickness of 500 μm is used. The mask is patterned by photolithography, and the ink recovery path 806 and the ink flying path 807 are etched by ICP-RIE. Thereafter, the mask is removed.

  In the fourth process shown in FIG. 12D, the upper part manufactured in the second process and the lower part manufactured in the third process are connected. An alignment mark for alignment is prepared in advance on a mask for processing each member. For connecting the members, direct bonding of the silicon surface may be used, or an adhesive may be used. In direct bonding, if the bonding is successful, the molecules are bonded by covalent bonding between molecules. Therefore, if the bonding surface has dust on the other side, extremely high bonding strength can be obtained. . In the case of using an adhesive, an epoxy adhesive or the like can be applied with a dispenser and bonded.

  In the fifth step shown in FIG. 12E, the electrode 809 and the wiring 808 connecting the electrodes are formed. Using oblique deposition, a metal thin film is formed on the top surface and the inner wall of the ink flight path. For the metal thin film, a metal thin film having corrosion resistance such as Au is suitable. In order to improve adhesion to the substrate, it is preferable to form a thin film of Ti or the like as a base layer. All electrodes need to be electrically connected so that the same voltage can be applied, but there is no need to control the voltage individually, so fine patterning is not required for wiring, for example, all the top surface of the substrate is deposited It may be in a state where

  Next, a gutter part is produced. In this embodiment, a silicon wafer having a thickness of 100 μm and double-side polishing is used as a substrate. A method for forming the gutter portion will be described with reference to FIG. A two-stage mask is formed in the same manner as in the first step, and a recovery path 810 and an ink flying path are formed by etching. ICP-RIE is used for etching. After etching, the mask is removed. Furthermore, it can also be used as an insulating spacer by forming an insulating film layer on the electrode plate surface. In this case, the third insulating spacer can be omitted.

  The gutter plate 814 produced as described above is connected to the second deflection electrode plate 104 produced in the fifth step (FIG. 12G). An alignment mark for alignment is prepared in advance on the mask of each member. For connecting the members, direct bonding of the silicon surface may be used, or an adhesive may be used. In direct bonding, if the bonding is successful, the molecules are bonded by covalent bonding between molecules. Therefore, if the bonding surface has dust on the other side, extremely high bonding strength can be obtained. . In the case of using an adhesive, an epoxy adhesive or the like can be applied with a dispenser and bonded.

  As in the first embodiment, the ink collection path 812 has a slit shape extending in the depth direction (second main direction). The shape of the ink flight path 813 is a slit shape extending in the depth direction (second main direction) (FIG. 13A), or an individual through hole corresponding to each passing droplet row (FIG. 13B). And

  In the description of the manufacturing process of the second deflection electrode plate 104 of this embodiment, a method is used in which the electrode members etched separately in the second and third processes are bonded in the fourth process. This is because when the aspect ratio of etching is increased, taper is formed and processing accuracy is deteriorated, and the etching rate is prevented from being lowered in the middle. Depending on the conditions of the diameter and depth of the through-hole of the electrode and the specifications of the etching apparatus to be used, it can be produced with one member, or conversely, etching is divided into more members, laminated, It is also possible to perform bonding.

  For the formation of the slit-shaped through hole, crystal anisotropic wet etching using KOH as an etchant can be used instead of ICP-RIE. At this time, a silicon nitride film is used for the mask, and a substrate whose surface is the (110) plane is used.

  In the manufacturing method of the first deflection electrode plate 103 and the second deflection electrode plate 104 of the present embodiment, a silicon wafer can be used as a substrate material, so that high aspect ratio etching can be realized with high accuracy. Is possible. As other materials, a plastic material, a ceramic material, or the like can be used as the substrate. When a plastic material is used, there is an advantage that an inexpensive and light electrode plate can be realized by using injection molding or the like for processing. When a ceramic material is used, it is produced by sintering or the like, but has an advantage that it is excellent in corrosion resistance to ink and has little expansion due to heat.

  Further, since a conductive layer must be formed, the manufacturing method is complicated as compared to the first embodiment, but all the electrodes may be at the same potential in each electrode plate. This eliminates the need for fine wiring and electrode patterning, and is much simpler than the case where the positive and negative deflection electrodes are formed in the same layer. The manufacturing method of other members, the method of assembling the inkjet head, the configuration of the inkjet device, and the operation method are the same as those in the first embodiment.

[Third embodiment]
A third embodiment of the present invention will be described. In this embodiment, another configuration of the second deflection electrode plate 104 will be described. In the first embodiment, the gutter and the ink recovery channel are formed on the second deflection electrode by etching. However, in this embodiment, the porous conductive material 901 capable of absorbing ink is used to deflect the second deflection electrode. The electrode serves as a gutter and a recovery channel. That is, the deflected charged droplet collides with the inner wall of the deflection electrode, and is sucked and collected from the porous portion.

  FIG. 14A shows a cross-sectional view of the second deflection electrode of this example. As a material, a porous body of a conductive member is used. In particular, those having corrosion resistance to ink are preferable. For example, stainless steel foam or porous carbon can be used. These porous materials can be processed by pressing or laser processing. In the case of a metal material, a desired porous shape can also be obtained by placing the powdered material in a mold and sintering it by a processing method called MIM (Metal Injection Modeling). The ink flying path 902 is formed using these materials and processing methods.

  Further, as shown in FIG. 14B, the upper surface and the lower surface of the second deflection electrode plate 104 may be sealed. As a sealing method, there are a method in which thin plates having through holes for ink flying paths are bonded together, and a method in which an adhesive sealant having a high viscosity and a high surface tension is applied and impregnated on the upper surface and the lower surface. Furthermore, as shown in FIG. 14C, a hollow channel (903) can be formed inside the porous portion, and the resistance of the recovery channel can be lowered.

  The manufacturing method of other members, the method of assembling the inkjet head, the configuration of the inkjet apparatus, and the operation method are the same as in the first embodiment. By using the second deflection electrode plate 104 using the porous conductive material in this way, the processing of the gutter portion can be omitted and the number of parts can be reduced.

[Fourth embodiment]
A fourth embodiment of the present invention will be described. In this embodiment, as shown in FIG. 15, the conductive surface of the inner wall of the through hole of the second deflection electrode is opposed to the first main direction across the droplet trajectory from the adjacent nozzle. ing. Moreover, it has a shape separated from the droplet trajectory corresponding to the adjacent nozzle on the opposite side by the conductive surface of the inner wall of the through hole. Specifically, compared with the configuration in FIG. 1 (FIG. 3), in FIG. 3, there was always a conductive surface of the inner wall of the through hole of the second deflection electrode between adjacent droplet trajectories. In FIG. 15, the conductive surface is provided every other nozzle. In FIG. 15, the inner wall is also provided every other nozzle, but if the conductive surface is not formed, there may be an inner wall (see the third manufacturing method described later). Other components are the same as those in the first embodiment.

  The first manufacturing method of the second deflection electrode plate 104 of the present embodiment is a method using a conductive substrate as the material, and is almost the same as the manufacturing method of the second deflection electrode in the first embodiment. However, the sizes of the ink flight path 602 and the ink recovery path 603 in FIGS. 8B and 8F are changed. That is, the ink flight path is widened, and the ink recovery path is every other nozzle. FIG. 16 shows a top view of the second deflection electrode plate 104 manufactured by the first manufacturing method of this example. Similar to the first embodiment, the ink recovery path 1003 has a slit shape extending in the second main direction. On the other hand, the shape of the flight path 1002 is a slit shape (FIG. 16A) extending over two nozzle rows, or a through hole (FIG. 16B) extending over two nozzles.

  Next, a second manufacturing method of the second deflection electrode plate 104 of this embodiment is shown in FIG. FIG. 19 shows a top view of the second deflection electrode plate 104 when manufactured by the second method. Similar to the second deflection electrode plate 104 manufactured by the first manufacturing method, the ink recovery path 1108 has a slit shape extending in the second main direction. On the other hand, the ink flying path 1109 has a slit shape (FIG. 19A) extending over two nozzle rows or a through-hole extending over two nozzles (FIG. 19B).

  The second manufacturing method is a method using an insulating substrate as a material, and is almost the same as the manufacturing method of the second deflection electrode in the second embodiment. However, the sizes of the ink flight path and the ink recovery path are changed according to the configuration of the present embodiment. For the formation of the electrode 1110, a conductive material film is formed on the inner wall of the substrate. Therefore, a highly isotropic film formation method such as sputtering is suitable. Alternatively, oblique vapor deposition with different angles may be performed twice.

  Next, FIG. 18 shows a third manufacturing method of the second deflection electrode plate 104 of this embodiment. FIG. 21 is a top view of the second deflection electrode plate 104 when manufactured by the third method. The third manufacturing method is a method using an insulating substrate as a material, and is substantially the same as the second manufacturing method of the present embodiment. The shape of the ink recovery path 1209 of the second deflection electrode plate 104 manufactured by this manufacturing method is a slit extending in the second main direction. On the other hand, the shape of the ink flying path 1210 is a slit shape (FIG. 19C) or an individual through hole (FIG. 19D) extending from the front surface to the back surface corresponding to each droplet row that passes. . Here, it is important that the electrode 1211 on the inner wall of the through hole and the wiring 1212 on the upper surface are not formed on the entire surface but on the side surface and the upper surface of the portion sandwiched between two droplet trajectories.

  In the third manufacturing method, since the electrodes are formed on the two opposing inner wall surfaces, oblique vapor deposition with different angles is performed twice (FIG. 18E). A significant difference from the second manufacturing method is that a mask is required to be formed in advance in order to prevent the conductive layer from being formed on portions other than the electrodes. The mask is formed by the method shown in FIG. 18A. What is important here is to form a mask shape that protrudes from the ink flight path so that a conductive layer is not formed on the inner wall even in oblique deposition. . A thick film resist or the like having high rigidity is used for the mask. After the mask is manufactured, as shown in FIG. 18b), the ink flight path and the ink recovery path are etched. Thereby, it is possible to form a mask that protrudes to the ink flight path. Further, if a film resist is used, a mask for oblique deposition can be formed after the ink recovery path is formed (after FIG. 18B). Further, by removing the mask after oblique deposition, the conductive layer formed on the mask can be removed together. If a conductive layer is formed on the side wall of the mask by oblique deposition and it is difficult to peel off, choosing a film-like material that is flexible and difficult to tear, such as parylene, will dissolve in the solvent. Instead of peeling, the mask can be peeled off.

  When the equipotential lines of the electric field at the deflection electrode and the trajectory of the charged droplet are simulated under the same driving conditions as in the first embodiment, the result is as shown in FIG. Three-dimensional nonlinear electrostatic field analysis software ELFIN (Elf Company) was used for the simulation. FIG. 20B shows a perspective view of the structural model used for the simulation. The charged droplet is deflected by 100 μm at a point of 860 μm from the upper end of the second deflection electrode plate 104. Therefore, a larger deflection amount than that of the configuration of the first embodiment is obtained.

  Here, the equipotential lines in the simulation result of the first embodiment (FIG. 10A) are compared. In the configuration of the first embodiment, the conductive surface of the second deflection electrode plate 104 with respect to the adjacent nozzle serves as a shield that blocks the electric field, and the electric field from the first deflection electrode plate 103 is the second deflection electrode. It hardly reaches the inside of the droplet flight path (through hole) of the plate 104.

  On the other hand, in the configuration of the present embodiment, the conductive surface of the inner wall of the second deflection electrode plate 104 is disposed so as to face each other across the adjacent droplet trajectory. That is, the conductive surface of the second deflection electrode plate 104 facing each other in the first main direction has a droplet flight path so as to sandwich the entrance trajectory axis of both droplets from two adjacent nozzles therebetween. Is defined. For this reason, the interval between the conductive surfaces of the inner wall of the second deflection electrode plate 104 is widened, and the electric field generated between the second deflection electrode plate 104 and the first deflection electrode plate 103 enters the droplet flight path of the second deflection electrode plate 104. doing. As a result, the charged flying droplets are affected by the electric field for a longer time, so that a larger deflection can be obtained. According to the simulation, the shape of the electric field is substantially mirror-symmetric with respect to the central axis between the two inner wall conductive surfaces facing each other of the second deflection electrode plate 104. Since the lines of electric force are perpendicular to the illustrated equipotential lines, when a negatively charged droplet enters from the right side with respect to the central axis, it is deflected to the right, and when it enters from the left side, it is deflected positively (charged). When the polarity of the electrode or the polarity of the deflection electrode is reversed, the electrode is deflected in the opposite direction). In this embodiment, the orbital axis of entry of droplets from the left nozzle into the deflection electrode through-hole is shifted 250 μm to the left in the first main direction from the central axis, and the deflection electrode of droplets from the right nozzle The approach orbit axis to the through hole is shifted by 250 μm to the right from the center axis. Accordingly, the charged droplet from the left nozzle receives an electrostatic force so as to be deflected to the left, and the charged droplet from the right nozzle receives an electrostatic force so as to be deflected to the right, as shown in FIG. Draw a trajectory that has been.

  The second deflection electrode plate 104 manufactured by the third method of this embodiment has an insulating portion between adjacent droplet trajectories. Since this insulating portion does not serve as an electrical shield, the electric field formed between the first deflection electrode plate 103 and the second deflection electrode plate 104 is the same as that shown in FIG. In particular, with this configuration, thanks to the insulating walls, there is no aerodynamic interference between droplets ejected from adjacent nozzles, and droplet flight is stabilized, so more accurate printing is performed. be able to.

  In this simulation, the charged droplet collides with the second deflecting electrode plate 104. After the collision, the charged droplet travels through the electrode plate and is finally collected by the lower gutter 005 (not shown). . Similarly to the third embodiment, the second deflection electrode plate 104 may be made of a porous material and may also serve as a gutter. Alternatively, the charging voltage or the deflection voltage is reduced or the thickness of the second deflection electrode plate 104 is reduced so that the charged droplet does not collide with the second deflection electrode plate 104 and directly hits the gutter portion. May be. Reducing the charging voltage and deflection voltage has the advantage that the power consumption can be reduced, and reducing the thickness of the second deflection electrode plate 104 has the advantage that the distance from the nozzle to the printing medium can be shortened and the printing accuracy can be increased.

  On the other hand, uncharged droplets are not deflected, fly linearly, and land on the print medium below.

[Fifth embodiment]
A fifth embodiment of the present invention will be described. FIG. 21 is a sectional view of the side surface of the ink jet head of this embodiment. FIG. 22 shows a perspective view of the first deflection electrode plate 103 of this embodiment (as viewed from the bottom side upside down). In the present embodiment, the configuration of members other than the first deflection electrode plate 103 is the same as that of the fourth embodiment.

  In the present embodiment, the first deflection electrode is provided with a protrusion 105 protruding toward the through hole of the second deflection electrode plate 104. The projecting portion 105 is disposed with respect to the two electrodes facing the first main direction of the inner wall of the through hole of the second deflection electrode plate 104 with the droplet flight trajectory interposed therebetween, and the second deflection electrode plate It does not enter the through hole.

  A first manufacturing method of the first deflection electrode plate 103 of this embodiment will be described. As shown in FIG. 23A, a conductive member having corrosion resistance such as stainless steel is used for the substrate. In this embodiment, the substrate thickness is 400 μm. As shown in FIG. 23 (b), a through-hole for allowing ink to pass through and a protrusion are formed. In the present embodiment, as shown in FIG. 22, the shape of the through hole is a cylindrical shape, and the hole diameter is 50 μm. The shape of the protrusion is a straight beam, the width is 300 μm, and the height is 200 μm. Etching, pressing, or the like can be used to form the through holes and the protrusions. Furthermore, in order to improve conductivity and corrosion resistance, the electrode plate surface may be plated with gold.

  Next, a second manufacturing method of the first deflection electrode plate 103 of this embodiment will be described. An SOI (silicon on insulator) wafer is used as the substrate. In this embodiment, the handle layer has a thickness of 200 μm, the BOX layer has a thickness of 1 μm, and the device layer has a thickness of 200 μm. First, the substrate is thermally oxidized to form a silicon oxide layer on the surface (FIG. 23C). Next, the formed oxide layer is patterned by photolithography. Using the patterned oxide layer as a mask, the front surface and the back surface are etched by ICP-RIE to form the through-hole (ink flight path) 113 and the protrusion 105. Further, the silicon oxide on the surface and the ink flight path is removed by hydrogen fluoride (FIG. 23D). Next, a metal to be an electrode is formed from the back surface (FIG. 23 (e)). A metal thin film having corrosion resistance such as Au is suitable for the electrode. In order to improve adhesion to the substrate, it is preferable to form a thin film of Ti or the like as a base layer. For the film formation, a method such as sputtering that facilitates film formation on the inner wall is suitable.

  When the equipotential lines of the electric field at the deflection electrode and the trajectory of the charged droplet are simulated under the same driving conditions as in the first embodiment, the result is as shown in FIG. Three-dimensional nonlinear electrostatic field analysis software ELFIN (Elf Company) was used for the simulation. A perspective view of the structural model used in the simulation is shown in FIG. The charged droplet is deflected by 100 μm in the first main direction at a point of 470 μm from the upper end of the second deflection electrode. Therefore, a larger amount of deflection is obtained than in the configurations of the first and fourth embodiments. There may be several reasons for this. Compared with the simulation result of the fourth embodiment (FIG. 20A), first, the electric field formed between the inner wall of the protrusion and the second deflection electrode is first perpendicular to the flight direction of the droplet. You can see that it is close to. Further, the distance between the electrodes is shortened due to the influence of the protrusions, and the density of equipotential lines formed therebetween is increased. Further, the equipotential lines can penetrate deeper into the through holes of the second deflection electrode plate 104. For these reasons, the charged droplets are largely deflected compared to the other embodiments.

  In the present embodiment, when the second deflection electrode plate 104 is produced by the same method as in the fourth embodiment, the droplet deflection track and the droplet trajectory are formed on the second deflection electrode plate 104 by the third manufacturing method. An insulating part is provided between the two. Since this member does not serve as an electrical shield, the electric field created between the first deflection electrode plate 103 and the second deflection electrode plate 104 is the same as that shown in FIG. In this case, the protrusion 105 is installed so as to oppose this insulating member. In particular, with this configuration, thanks to the insulating walls, there is no aerodynamic interference between droplets ejected from adjacent nozzles, and droplet flight is stabilized, so more accurate printing is performed. be able to.

  In this simulation, the charged droplet collides with the second deflecting electrode plate 104. After the collision, the charged droplet travels through the electrode plate and is finally collected by the lower gutter 005 (not shown). . Similarly to the third embodiment, the second deflection electrode plate 104 may be made of a porous material and may also serve as a gutter. Alternatively, the charging voltage or the deflection voltage is reduced or the thickness of the second deflection electrode plate 104 is reduced so that the charged droplet does not collide with the second deflection electrode plate 104 and directly hits the gutter portion. May be. Reducing the charging voltage and deflection voltage has the advantage that the power consumption can be reduced, and reducing the thickness of the second deflection electrode plate 104 has the advantage that the distance from the nozzle to the printing medium can be shortened and the printing accuracy can be increased. On the other hand, uncharged droplets are not deflected, fly linearly, and land on the print medium below.

  As described above, it can be understood that the charged droplets can be deflected more efficiently by providing the protrusion 105 on the first deflection electrode plate 103. In addition, since the height of the protrusion does not enter the through hole of the second deflection electrode, the protrusion does not require high accuracy in assembling the ink jet head.

  Since the liquid discharge head of the present invention has nozzles in a two-dimensional array, it can be used to realize a high-speed and high-definition liquid discharge apparatus. Also, the method for manufacturing a liquid discharge head according to the present invention can be used for manufacturing a low-cost liquid discharge head with a small number of components because a head corresponding to a multi-nozzle can be manufactured by laminating layered deflection electrode plates. be able to.

004 Head 101 Orifice plate 102 Charging electrode plate 103 First deflection electrode plate 104 Second deflection electrode plate 105 Protrusion 111 Nozzle 112 Charging electrode through hole 113 First deflection electrode through hole 114 Second deflection electrode through hole 201 First insulating spacer 202 Second insulating spacer 203 Third insulating spacer

Claims (6)

A nozzle member having a plurality of nozzles for ejecting liquid droplets arranged two-dimensionally along a first direction and a second direction different from the first direction;
A charging member having a charging electrode for applying a charge to the droplets discharged from each of the plurality of nozzles;
A first deflecting member and a second deflecting member each having a deflecting electrode for deflecting each of the droplets charged by the charging electrode,
Said charging member, the first deflection member, and the second deflection member has a through hole for passing the droplets discharged from the plurality of nozzles, respectively,
It said charging member, the first deflection member, and the second deflection member is laminated in the direction in which liquid droplets are ejected from each of the plurality of nozzles in this order,
The second deflecting member has a conductive surface corresponding to each of the plurality of nozzles on an inner wall of each of the through holes,
The conductive surfaces of the second deflecting members facing each other in the first direction define a droplet flight path so as to sandwich the entrance trajectory axis of both droplets from two adjacent nozzles therebetween. And
The liquid ejection head, wherein the first deflecting member includes a projecting portion that protrudes toward the through hole of the second deflecting member and has a conductive surface constituting the deflecting electrode .   The liquid ejection head according to claim 1, wherein the second deflecting member is formed of a porous body that can absorb the liquid droplets. 2. The liquid ejection head according to claim 1, wherein the protrusion is disposed so as to be sandwiched between two approach trajectory axes of droplets from the two adjacent nozzles . Between the nozzle member and the charging member, between the charging member and the first deflection member, between the electrode plates of the first deflection member and the second deflection member, each liquid discharge head according to claim 1, insulating member having a through hole through which the droplets pass is interposed, it is characterized. The charging member has the charging electrode formed on the inner wall of the through hole, and a wiring drawn from the charging electrode,
Each of the first deflection member and the second deflection member includes a deflection electrode formed on an inner wall of the through hole, and a wiring that electrically connects the deflection electrodes. The liquid discharge head according to claim 1. 2. The liquid ejection head according to claim 1, wherein the deflection electrodes of the first deflection member and the second deflection member are connected to each other so as to have the same potential. .

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